This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-206820, filed Jul. 7, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a wiring case for housing a plurality of receiving devices (devices to be controlled) such that each of which can establish data and electric communications with a transmitter device (control device) via two power lines.
2. Description of the Related Art
Conventionally, a two-wire type data and electric transmission/reception communication system is known as a technique for carrying out data and electric transmission/reception communication which is conducted with use of two power lines (that is, a technique for carrying out transmission/reception of power (electricity) and data communication at the same time) (cf. Japanese Patent No. 27887976). In this system, one transmitter-side device and a plurality of receiver-side devices are connected together via two power lines. While a power which contains data component is transmitted from the electric transmitter device, the electrical charge and data decoding are carried out on the side of a receiver device. When the electrical transmission is stopped in the transmitter side, the receiver device a power containing data addressed to the transmitter device is sent on the basis of the charged power. In this manner, the transmission/reception communication of electrical power and data can be carried out between one and n-number devices with a less amount of wiring.
In some cases of the actual application of such a two-wire data and electric transmission/reception communication system, the number of receiver devices becomes 20 to 30 or even more, or the site where a receiver device is mounted must be charged from one place to another frequently. Under these circumstances, it is very important to carry out the wiring operation for connecting the transmitter device and the receiver devices with each other at high efficiency. In view of increasing the efficiency of the wiring operation, it is effective to use a wiring duct base as discussed in Japanese Patent Application KOKAI Publication No. Hei10-177353.
Such a wiring duct base has a substrate portion and engagement portions formed along both sides of the substrate, and has a flat-plate shape in which at least two tape-like conductive members for transmitting electrical signals are provided on the surface of the substrate along its longitudinal direction. A receiver device is formed into a unit (display unit), and a conductive member electrically connected to the receiver device is provided on the rear surface side of the unit, with stopper portions being formed at both end sides. As the stopper portions engage with the engagement portions of the wiring duct base, the display unit is mounted on the front surface of the wiring duct base. As it is mounted, the conductive member located at the rear surface section of the display unit is brought into contact with the tape-like conductive member to be electrically connected thereto. The strength of the engagement of the stopper portions and engagement portions between the display unit and the wiring duct base is set such that the strength on one end is looser than that of the other end, and the display unit is detached from the wiring duct base from the looser engagement end.
With the wiring duct base having the above-described structure, the display unit can be mounted at an arbitrary position. Further, since the wiring has been provided in advance, a further wiring operation is not required when replacing the unit.
In the two-wire data and electric transmission/reception communication, generally, a large-capacity power is allowed to flow in a conductive member. Therefore, a pair of conductive members must be kept away from each other by a certain distance or more so that mutual interference, that is, one conductive member being interfered with the power of the other one, can be avoided. Further, the conductivity of each conductive plate is determined by a product of its cross sectional area and surface dimension (cross sectional area x surface dimension), and therefore when the conductivity is lowered, the decrease in voltage is lessened accordingly.
However, the conventional wiring duct base has engagement portions formed at both ends, and therefore there is a certain limit to the area in which conductive plates can be installed. In the case where it is possible to assure a sufficient width of a section where a wiring unit is mounted (that is, the width of the wiring unit), there will be no problem since the width of the wiring unit can be increased. However, in the case where it is not possible, the cross sectional area and surface dimension of each conductive plate cannot be increased, and therefore it becomes difficult to mount such a great number of display units.
Further, the conventional wiring duct base has engagement portions on its both sides, and the display unit has stopper portions. With this structure, it requires a great force to detach a display unit from the wiring duct base, which results in a poor operability in replacement of the unit.
The present invention has been proposed to solve the above-described drawback of the conventional technique, and its object is to provide a wiring case having an excellent operability, which can assure a sufficient size of conducting members and an interval between conductive members.
According to a first aspect of the present invention, there is provided a two-wire type wiring case for mounting a device to be controlled, which establishes data and electric transmission/reception communication with a predetermined controller, the device having a front surface portion provided thereon with an electronic circuit operable by the data and electric transmission/reception communication, side portions provided thereon with respective elastic engagement mechanisms, and a rear surface provided thereon with a pair of projecting portions each having at a tip end thereof a first conductivity member electrically connected to the electronic circuit, the wiring case comprising: a long-scale mount portion for detachably mounting the device, the long-scale mount portion comprising: a pair of second conductivity members provided in a band-like arrangement in a longitudinal direction at positions which are respectively contactable with the pair of first conductivity members, the pair of second conductivity members having a gap provided therebetween for avoiding an interference of one of the second conductivity members, the interference being otherwise caused due to power flowing through the other of the second conductivity members when the pair of second conductivity members are energized; and fixation mechanisms provided at positions remote from the pair of second conductivity members, for detachably fixing the device, by engaging with the respective elastic engagement mechanisms, wherein the pair of first conductivity members are brought into contact with the second conductivity members respectively when the device is mounted onto the wiring case so that data and electric transmission/reception communication between the mounted device and the controller is established when the second conductivity members are electrically connected to the controller.
As described, the fixation mechanisms of the long-scale mount portion are formed at side end portions thereof so that they are located as far away as possible from the second conductivity members. With this structure, the width of each second conductivity member and the distance between second conductivity members (conductive plates) can be widened as compared to the case the fixation mechanisms are formed near the second conductivity members. As the width of each second conductivity member can be increased, the conductivity of the second conductivity member is increased, thus making it possible to suppress the drop of voltage. In this manner, it is possible to increase the number of devices, which can be installed.
It may be arranged that the long-scale mount portion has a shape of substantially U in a cross section perpendicular to the longitudinal direction, and the pair of second conductivity members are provided on an inner bottom surface of the long-scale mount portion.
With this structure, the area of the bottom surface portion, which is defined by one end in the longitudinal direction and the other side, can be used for the installation of the second conductivity members. Therefore, it is possible to increase the number of devices, which can be installed.
It may be arranged that the front surface portion of the device, has a display portion, and the wiring case further comprises an outer wall portion used for fixing the long-scale mount portion to a desired position, and when the device is mounted to the long-scale mount portion, a plane including the display portion of the device and a plane including the outer wall portion make a predetermined inclining angle.
With this structure, it is possible to set the display portion of the device inclined at a desired angle with respect to the outer wall portion of the long-scale mount portion when the device is mounted on the wiring case.
It may be arranged that the front surface portion of the device, has a display portion, and the wiring case has first and second outer wall portions used for fixing the long-scale mount portion to a desired position, and when the device is mounted to the long-scale mount portion, a plane including the display portion of the device, a first plane including the first outer wall portion and a second plane including the second outer wall portion make predetermined inclining angles with respect to each other, and the first plane and the second plane cross with each other on a rear surface side of the mounted device. In this two-wire type wiring case, it may be arranged that the first plane and the second plane cross with each other at right angles.
With this structure, the first outer wall portion and second outer wall portion are fixed to tightly fit the corner portion of the wall where the wiring case is mounted, and thus the wiring case can be mounted to tightly fit with the corner portion. In most of the cases, the corner portion is made at right angles, the first plane and second plane are made orthogonal in a preferable situation.
It may be arranged that the long-scale mount portion has a bent portion for creating a gap between the pair of second conductivity members, and a part of a plane of the bent portion is made in parallel with the first plane.
With this structure, the amount of material used to prepare the long-scale mount portion, can be reduced as compared to the case where the gap is entirely filled with the material which constitutes the long-scale mount portion. Further, when the elasticity of the material is set to an appropriate value, this bent portion becomes to serve as a kind of a spring, thereby making it possible to achieve a cushion-like effect in the wiring case itself while maintaining a sufficient rigidity required as a wiring case.
It may be arranged that the elastic engagement mechanisms are engaged with the fixation mechanisms, when a body of the device is pressed towards the long-scale mount portion, and disengaged from the fixation mechanisms when both side end portions of the device are held by hand so as to deform the device as a whole towards a central line along the longitudinal direction.
With this structure, when the device is held, the engagement mechanisms are released from the fixation mechanisms, thus making it possible to attach or detach the device very easily.